Implementation of Self-Consolidating Concrete for Bridge Applications

Self-Consolidating Concrete (SCC) typically refers to a highly-flowable classification of high-performance concrete. Unlike traditional concrete, SCC has the potential ability to flow into and completely fill complex forms under its own weight. A well-designed SCC mix does not need to be vibrated for compaction, unlike a traditional vibrated concrete (TVC) mix. This gives the use of SCC the potential advantages of reduced placement costs and a more worker-friendly construction environment due to the elimination of construction noise and the added ease of placement. The primary objective of this study was to work with contractors, WVDOT officials in order to safely utilize SCC technology on the Stalnaker Run Bridge Replacement, which would be the first WVDOT bridge construction project to utilize SCC. SCC was incorporated for cast-in-place caissons as well as precast/prestressed beam components.;Prior to use of a 4,500 psi mix for the caisson applications, deemed SCC-1, a novel test procedure was developed to assess the uniformity of SCC within a model caisson member. Instead of allowing the entire mock section of SCC to harden prior to dissecting it for core samples, fresh core tubes were used to sample the SCC while it was still green. After hardening, the wet cores revealed non-uniformities in the aggregate distribution and hardened properties of the mix as placed within the trial caisson. Despite the non-homogeneity, tests did not indicate a relationship between the absence of aggregates and detrimental effects on the hardened properties of the SCC-1.;SCC-1 was used for the construction of the caissons of Abutment 1, while a traditional caisson mix was used for Abutment 2. Samples taken during casting of the caissons revealed that both caisson mixes exceeded the minimum strength requirement, and specimens of both types exhibited approximately the same modulus of elasticity, around 4,400 ksi. The SCC-1 mix exhibited low Rapid Chloride Permeability and was deemed freeze-thaw durable based on ASTM C 666 testing.;Three precast/prestressed box beams for the Stalnaker Run Bridge were fabricated using a traditional vibrated concrete and two were cast using SCC-2, both of which required a strength of 8,000 psi. Additionally, one extra beam was fabricated and shipped to WVU facilities for testing. All beams were instrumented with a barrage of gages prior to casting. After casting, the SCC-2 mix required 2 nights of steam curing prior to detensioning, while the TVC needed only one. Temperature data collected during curing of the beams indicated maximum temperatures of around 160°F to 170°F, which fall below the PCI-prescribed threshold of 180°F. Specimens collected during construction of the Stalnaker Run Bridge showed some major differences in the hardened behaviors of SCC-2 and TVC. The TVC has a higher modulus of elasticity than the SCC-2 concrete, both at detensioning (19% higher) and at 28 days (21.0% higher). Durability testing of SCC-2 specimens indicate that the SCC-2 concrete from production may not be freeze-thaw durable, and not all specimens exhibited the required durability factor of 80% per project specifications. Results of RCPT testing of both types of concrete would classify SCC-2 as having predominately moderate permeability, while the TVC would be classified as having high permeability.;The laboratory beam underwent both destructive and non-destructive testing. The effective prestress in the beam calculated using the observed decompression behavior of the beam (Pe = 707.5 kips or fpe = 159.7 ksi), was within 1.5% of a direct measurement of the residual strain based on strand strain readings, which were taken directly from the strand strain gage readings. The test beam exhibited higher deflection and lower capacity at cracking than the theoretical behavior using PCI design values. Adjustments of the material properties to measured values for SCC-2 gave a good correlation between theoretical and observed load-deflection behaviors. The results of the non-destructive modal analysis did not correlate well with the damage state of the prestressed beam.;Strain data from the Stalnaker Run Bridge data collection station is being collected incrementally. Over a four month period, the magnitudes of measured strain change in the prestressing strand gages ranged from 200 microstrain to 400 microstrain, and 200 microstrain to 500 microstrain for the SCC-2 and TVC beams, respectively. The rate of change in the strain readings for the beams has since decreased drastically